Voxel or not (I suspect not) it does appear to be mapping in world space. I suspect they blend unique maps on modular assets with the world space tiling maps - it'd be my starting point if I were to try and recreate the look. I wouldn't get too bogged down in the specifics of how tbh. you could do the effect in screenspace…
Triplanar mapping is just world space projection in 3 axes with a blend based on mesh normals - theres no magic there. The screenspace thing was semi facetious. You could do all the projection and texture application in screenspace as a post process effect if the mood took you (it's probably not a sensible approach though)…
I was pretty sure it wasn't voxels (mainly due to the seams on some assets), but was laying it out there just in case. I think you're onto something there. I definitely noticed the modular assets in some places. What throws me off about them is that some of the tiles appear to be blended really well with the geometry…
@astraldata Slopes are a bit problematic. Say you have a three-tile long strip and compare a flat plane versus planes covering the same distance but at different angles to meet different heights. The angled planes are longer, and if they are mapped for their distance, you'll have seams at one end. So as an exercise in…